Description:
In this study two scenarios are considered to study the digestate treatment process in which liquid fertilizer and compost are produced. The process simulation model by Aspen Plus have been utilized to simulate the anaerobic digestion (AD) process and the general properties of biogas and digestate. The results of the technical analysis for electricity generation show that although usage of a digestate treatment process affects the net power production of the CHP unit, it is not considerable. Furthermore, the economic analysis indicates that using a digestate treatment process is necessary for AD systems to be profitable. The results from environmental analysis also show that digestate treatment process reduces 646000 tonnes of greenhouse gas (GHG) emission while an AD unit that does not have a digestate treatment process saves only 12000 tonnes of GHG emissions. The reason for this phenomenon is that the digestate treatment process reduces the production and usage of chemical fertilizers in agriculture industry, and this type of fertilizer consumes a considerable amount of energy for its production. Results of this research prove the necessity of a digestate treatment process for AD systems using dairy manure as its feedstock